Copper cathode is produced by an electrolytic refining process of dissolving copper from copper anodes that are about 98-99% copper by weight. By virtue of placing the impure copper anode into an electrolyte solution under the influence of a pre-determined current density, copper ions from the anode migrate to a cathode which is normally made of a stainless steel starter sheet. Such a migration of the copper ions selectively plates the dissolved copper in “pure” form onto the stainless steel cathode, the thickness of which increases as the electrolytic refining process proceeds. Furthermore, metals that are more electropositive than copper tend to remain insoluble and separate out as impurities collecting at the bottom of the cell as a slime. The deposited copper on the cathode is approximately 99.99% pure copper. However, due to a variety of factors, such as variation in current density, minor quantities of impurities including, for example, bismuth, arsenic and antimony, can be trapped in the deposited copper.
The presence of such impurities can be highly undesirable, especially in specialty applications like manufacturing of integrated circuits where the effectiveness of the circuits is sensitive to any increase in impurity. Therefore, samples are frequently taken for conducting purity analysis of the manufactured copper cathode. The typical sample is a quarter-size disk of ½ to one inch in thickness punched from a copper cathode sheet. The sample is collected in a bucket or similar container. However, the operation of the production line is often disrupted either to empty the collection bucket between different batches of copper cathode to prevent mixing of samples from different batches or simply to replace a full bucket with an empty bucket. Such disruptions can accumulate over extended periods of time to the extent that a full day's production can be lost over the period of a month. This, in turn, can result in significant monetary losses to the manufacturer. Moreover, present sampling techniques require constant supervision of the sampling process to replace, sort, store and track the samples and buckets. Productivity can further be limited by the size of the sampling regime, i.e., the more cathode copper sampled, the more production disruptions and the more supervision of the sampling operation is required.
In consideration of the above problems, manufacturers of copper cathode have an interest in a system that continuously collects, sorts and stores copper cathode samples without disrupting the progress of the production line. Advantageous of such a system would include minimum supervision; the collection, sorting and storage of samples from different batches; and infrequent and easy maintenance of the equipment.